The dramatic rise in community-based S. aureus infections, many due to methicillin resistant S. aureus (MRSA), has become an important public health problem. This proposal will focus on prisoners, a high-risk group that has received limited attention. Prior studies have examined prison outbreaks without addressing several critical questions. These questions include the role of S. aureus colonization in the prison environment, how S. aureus is introduced into prisons and what the modalities of S. aureus persistence and transmission are in the nonepidemic prison setting. Our long term goal is to develop strategies that will prevent and control transmission of S. aureus within the prison system as well as in similar crowded environments. Our specific aims are the following. 1) We will identify patterns of S. aureus strain transmission within the prison. A cross-sectional analysis of prisoners will be performed to determine the prevalence of S. aureus colonization and/or infection. The role of assigned activities, environmental exposures, prisoner contacts and their spatial proximity in S. aureus transmission will be examined. Bacterial factors associated with the predominance of particular clones of S. aureus will be examined. 2) We will determine the factors associated with the development of clinical infections within the prison. A subset of inmates with culture proven S. aureus infections will be studied in a nested case-control study to determine factors contributing to symptomatic infection in the prison. 3) We will identify risk factors associated with colonization and/or infection with S. aureus at prisoner intake and at release. New prison inmates will be interviewed cultured and their prison/jail records reviewed. Risk factors predictive of S. aureus colonization/infection on arrival will be identified. Because >600,000 prisoners are released into the community each year, they can serve as an important reservoir for staphylococcal transmission. Therefore, S. aureus colonization at the time of release will also be assessed and factors contributing to colonization at release will be examined. This proposal provides an unparalleled opportunity to examine transmission of S. aureus (including MRSA) within the prison setting. The ongoing collaboration of prison personnel with the investigators is unique as is the integration of methodological approaches that will allow us to examine the roles of networks coupled with spatia characteristics in prisons. PUBLIC HEALTH RELEVANCE: This proposal will focus on prisoners, a group at particularly high risk for these infections. The study will investigate how S. aureus is transmitted in this population.